我正在尝试使用Java检索javascript变量.我认为我已经接近解决方案.

我想在面板上检索元素的宽度.为此,我在面板中添加了一个行为,该行为添加了回调并检索了参数(宽度和高度).

private class ImageBehavior extends AbstractDefaultAjaxBehavior {

    @Override
    protected void respond(AjaxRequestTarget target) {
        //I receive a JavaScript call :)
        StringValue width  = getRequest().getRequestParameters().getParameterValue("width");
        StringValue height = getRequest().getRequestParameters().getParameterValue("height");       
    }

    @Override
    protected void updateAjaxAttributes(AjaxRequestAttributes attributes) {
        super.updateAjaxAttributes(attributes);
        attributes.getExtraParameters().put("width", "undef");
        attributes.getExtraParameters().put("height", "undef");
    }

    @Override
    public void renderHead(Component component, IHeaderResponse response) {
        super.renderHead(component, response);
        response.render(OnDomReadyHeaderItem.forScript(getCallbackScript().toString()));

    }
}

在javascript中,以下代码被调用：

function callbackWicketNewImage(element) {
    var wcall = Wicket.Ajax.get({ 'u': 'callbackUrl', 'ep' : {'width': element.width(), 'height': element.height()}});
}

调用js代码时,将调用’respond’方法,但width和height参数的值未更改.他们仍然是“ undef”.

解决方法:

我用以下代码解决了我的问题.请注意,抽象的onResponse方法用于抽象目的.

public abstract class SizeBehavior extends AbstractDefaultAjaxBehavior {

@Override
protected void respond(AjaxRequestTarget target) {
    IRequestParameters request = RequestCycle.get().getRequest().getRequestParameters();
    onResponse(request.getParameterValue("widthParam").toDouble(),
            request.getParameterValue("heightParam").toDouble());
}

@Override
protected void updateAjaxAttributes(AjaxRequestAttributes attributes) {
    super.updateAjaxAttributes(attributes);
    attributes.getDynamicExtraParameters()
    .add("return {'widthParam': $(" + getComponent().getMarkupId() + ").width(), " +
                 "'heightParam': $(" + getComponent().getMarkupId() + ").height()}");
}

public void renderHead(Component component, IHeaderResponse response) {
    response.render(OnLoadHeaderItem.forScript(getCallbackScript().toString()));
}

public abstract void onResponse(double width, double height);
}  

行为调用：

add(new SizeBehavior() {
    @Override
    public void onResponse(double width, double height) {
        //set vars..
        widthVar = width;
        heightVar = height;
    }
});